Cavity-enhanced sacrificial layer micromachining for faster release of thin film encapsulated MEMS

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Cavity-enhanced sacrificial layer micromachining for faster release of thin film encapsulated MEMS
Title:
Cavity-enhanced sacrificial layer micromachining for faster release of thin film encapsulated MEMS
Journal Title:
Journal of Micromechanics and Microengineering
Keywords:
Publication Date:
15 May 2015
Citation:
Abstract:
This paper reports a method for fast-release and safe-sealing of thin film encapsulation (TFE) for packaging of piezoelectric MEMS devices fabricated on cavity-SOI wafers. For fast releasing of the TFE, MEMS device trenches and the cavity below them were utilized and this combination acted as etch channels. Etchant can attack the sacrificial layer from the bottom of the MEMS device as well as side-located channels. A side-located etch channel scheme was chosen to ensure safe-sealing without mass-loading. 120 μm × 120 μm sized encapsulation on top of the MEMS device with eight isolation trenches connected to the cavity was released in 25 min. This is twice as fast as the TFE fabricated on bulk wafer using a similar encapsulation scheme. This reduction in release time is a consequence of a prefabricated cavity underneath the device which allows the etchant to attack the sacrificial layer at multiple locations as etchant can pass from one isolation trench to another.
License type:
PublisherCopyrights
Funding Info:
Description:
ISSN:
0960-1317
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